Pyrometer tube



Aug. 26, 1930. F. c. slMMs 1,773,826

PYROMETER TUBE Filed July 14, 1928 INVENTOR Fanh C. Simms BY`7(/777 ZATTORNEY Patented Aug. 26, 1930 UNITED STATES FRANK C. SIMMS, F EASTPALESTINE, OHIO PYROMETER TUBE Application led July 14,

My invention relates to temperature measuring devices, and particularlyto pyrometer tubes.

An object of my invention is to provide a unitary structure for acomposite pyrometer tube that shall permit of the tube being quicklyinserted in and withdrawn from the chamber of a furnace without dangerof breaking or cracking.

Another object of my invention is to provide a unitary pyrometer tubestructure that shall embody a gas tight inner refractory member, aheat-equalizing intermediate ceramic member, and an outer highlyrefractory and gas and slag resistant member. These three elements arepreferably made each in the form of a tube, closed at one end and openat the other, and in intimate Contact with each other over theirengaging surfaces.

In practicing my invention, I provide a laminated tube structurecomprising an inner tube closed at one end, made of ceramic material andfired or burned at such heat as to ensure vitrifaction, an intermediatetube also closed at one end molded or placed on the inner tube andcomposed of such ceramic materials as to permit of reasonably slowpenetration thereof by heat, and an outermost coating or tube ofsuitable thickness, and composed of a ceramic material which willprevent slag from penetrating the bodies of the other tubes.

In the single sheet of drawings, Figure l is a view, in longitudinalsection, of a pyrometer tube embodying my invention,

and

Fig. 2 is a view, in Vertical lateral section of a furnace, showngenerally only, with which is associated the device embodying myinvention.

rIhe pyrometer tubes used heretofore have been made of a material whichhad to be handled very carefully in actual use, the tube being insertedin and withdrawn from a high rate of movement in order to preventfracture thereof. If a tube 0f this kind was inserted into a furnacechamber very quickly the effect of the high heat was such as to causethe tube to crack or break.

temperature furnace chamber at a very slow 1928. Serial No. 292,859.

Referring more particularly to Fig. 1 of the drawings, I have thereillustrated a laminated pyrometer tube 11 embodying an inner tube 12which is preferably made of a hard, dense clay, such as is used forporcelain articles and which has been fired at a temperature ofapproximately 2000 F.

An intermediate tube 13 is located therearound and in intimateengagement therewith, the material of this tube being a mixture ofcomminuted fused alumina,a high temperature clay, and a small amount ofa. suitable binder such asdextrine. I prefer to use a mixture of 30% ofhigh temperature cla and approximately of fused alumina, a 65 though Idesire it to be understood that these proportions are illustrative onlyand may be departed from to a certain' extent. Enough suitable binder isadded to the finely divided clay and the fused alumina to make a rela-70 tively moist mixture of the general consistency of heavy cream.

The tube 12, which may be of any desired thickness on the order of from1/8 to 5% inch wall thickness and which is closed at one end as shown,may be dipped into the moistened mixture of clay and alumina asufficient number of times to provide a relatively thick closelyadherent coating around the exterior of the tube 12. It may be necessaryto permit the coating obtained by each dipping to dry for a short periodin air before another coating is applied. A sufiicient number ofdippings are made to provide a relatively thick coating or tube 13,which thickness may be equal to or slightly greater than the thicknessof the wall of tube 12. I may also mold the fused alumina and claycoating around or on the inner tube.

An outer tube or coating 14 is provided and 90 I may make this of aceramic material suitable for the desired purpose, such as magnesite orzirconium, the method of application being substantially the same as washereinbefore set forth in connection with the coating 13. The Outerlayer or coating may be applied as soon as the last layer of coating 13has been thorf oughly dried.

I prefer, as noted above, to lire the porcelain tube 12, which I make inany suitable 10 or desi-red manner well knorm in the before applyingthereto the two outer tubes orv coatings as explained above. .rfterthese'plurality of coatin s have been thorou dried in air l place t etube in a suitabe -rurnace chamber operating at a temperat re 'of notless than 20009 F and ossibly up to 390? F. rEhe firing is continueuntil the inner tube 12 has been vitried or re-fused to a greater extentthan occurred during its initial hring,`

whereby it is rendered substantially gastight. Referring to Fig. 2 ofthe drawings, l have there illustrated a furnace structure 15 comprisinga plurality-of walls of heat-insulating and high temperature resistingbricks or blocks surrounding a furnace chamberA 15' Any suitable means(not shown) may be provided to heat the furnace chamber. an o ening 16is provided in one of the walls w ich is of such size'as to receive thepyrometer tube structure 11.

A thermocouple 17 is located within the pyrometer tube assembly 11 thetube extending suciently far into the furnace to subJect thethermocouple joint to the operating temperature existing in the chamber.Suitable indicating means (not shown) are connected to the two wires ofthe thermocouple to indicate the temperature, all as well hown in theart.

My improved laminated pyrometer tube structure is particularly adaptedfor use in furnaces in which special processes are being effected whichgive rise to fumes which attack ordinary ceramic materials, or infurreaches the innermost tube is substantially lib' uniformlydistributed, thereby avoiding the possibility of breakage of the innertube by reason of one portion thereof being at a temperature differentfrom that of another portion. Finally, the outermost coating 14 providesa slag, gas, and fume resistant coat@ ing so that the'unitary tubestructure embodying my invention can be used a relatively large numberof times without any apprecia le sign of the material having beenattached. I find it possible to insert a tube of this kind quickly intoafurnace or to withdraw it quickly from a furnace without danger of suchthermal shock as would ordinarily result in fracture ofa single layertube.v

The intermediate' coating or tube V13 has such thermal conductivity aswill appreciably Second, an intermediate tube of such material andoharacteristlcs as to withstand smittenV thermal shock. This tube orlamination-absorbs the heat relatively slowly and prevents a sudden heatshock from injuring 'the inner tube. Third, an outer lamination or tubeof a suitable ceramic lmaterial adapted to withstand the penetratingaction of slag'and fumes, to thereby save the other two tubes from theinjury which may be caused by slag found in various types of furnaces.

Various modifications may be made in the device embodying my inventionwithout departing'from the spirit and scope thereof, and I desiretherefore that only such limitations shall be placed thereon as areimposed by the prior art or are set forth in the appended claims.

ll claim as my invention t-f L'As a new article of manufacture of theclass described, a unitary laminated pyrometer tube structure comprisingan inner highly refractory gas-tight tube of ceramic material, anintermediate tube of a refractory material constituting a heat shieldfor the inner tube, and an outer tube of a slag and fume resistantrefractory material, all of said tubes being intimately bonded with eachother by firing' the outer tubes and the inner tube as a unit.

2. As a new article of manufacture of the class described, a unitarytriple wall pyrometer tube structure comprising an inner gastight layerof highly refractory ceramic material, an intermediate layer of arefractory material constituting a heat shield for the inner tube, andan outer coating of a slag and fume resistant refractory material, eachof said layers being in intimate engagement with an adjacent layer andbonded thereto by firing the outer layers in position upon the innerlayers.

3.' As a new article of manufacture of the class described, a unitarytriple wall pyromlain, an intermediate layer of a mixture of fusedalumina and a high temperature clay, and an outer layer of magnesite,eachv of said layers being in intimate engagement with an adjacentlayer, the intermediate and outer v layers` being coated upon theadjacent inner layer and bonded thereto by rin-g said layers. i

4. As a new article of manufacture of the class described, a unitarytriple wall pyrometer tube comprising a doubly fired inner layer ofporcelain-like ceramic material, a singly fired intermediate layer offused alumina and a high temperature clay, and a singly fired outerlayer of a slag and fume reslstant ceramic material, each of said layersbeing .in intimate engagement with an adjacent layer and bonded theretoby the firing of the outer layers.

In testimony whereof I aiix my signature.

FRANK C. SIMM-Q`

